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VIRTIS-H observations of the dust coma of comet 67P/Churyumov-Gerasimenko: spectral properties and color temperature variability with phase and elevation

Bockelee-Morvan, D. and Leyrat, C. and Erard, S. and Andrieu, F. and Capaccioni, F. and Filacchione, G. and Hasselmann, P. and Crovisier, J. and Drossart, P. and Arnold, Gabriele and Ciarniello, M. and Kappel, David and Longobardo, A and Capria, M. T. and De Sanctis, M.C. and Rinaldi, G. and Taylor, F. (2019) VIRTIS-H observations of the dust coma of comet 67P/Churyumov-Gerasimenko: spectral properties and color temperature variability with phase and elevation. Astronomy & Astrophysics, 630, A22. EDP Sciences. doi: 10.1051/0004-6361/201834764. ISSN 0004-6361.

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Official URL: https://www.aanda.org/articles/aa/abs/2019/10/aa34764-18/aa34764-18.html


We analyze 2-5 μm spectroscopic observations of the dust coma of comet 67P/Churyumov-Gerasimenko obtained with the Visible InfraRed Thermal Imaging Spectrometer (VIRTIS-H) instrument on board Rosetta from 3 June to 29 October 2015 at heliocentric distances rh = 1.24-1.55 AU. The 2-2.5 μm color, bolometric albedo, and color temperature were measured using spectral fitting. Data obtained at α = 90° solar phase angle show an increase in bolometric albedo (0.05-0.14) with increasing altitude (0.5-8 km), accompanied by a possible marginal decrease in color and color temperature. Possible explanations include dark particles on ballistic trajectories in the inner coma and radial changes in particle composition. In the phase angle range 50°-120°, phase reddening is significant (0.031%/100 nm deg-1) for a mean color of 2%/100 nm at α = 90°, which might be related to the roughness of the dust particles. Moreover, a decrease in color temperature with decreasing phase angle is also observed at a rate of 0.3 K deg-1, consistent with the presence of large porous particles, with low thermal inertia, and showing a significant day-to-night temperature contrast. Comparing data acquired at fixed phase angle (α = 90°), a 20% increase in bolometric albedo is observed near perihelion. Heliocentric variations in dust color are not significant in the time period we analyzed. The measured color temperatures vary from 260 to 320 K, and follow a rh-0.6 variation in the rh = 1.24-1.5 AU range, which is close to the expected rh-0.5 value.

Item URL in elib:https://elib.dlr.de/130753/
Document Type:Article
Title:VIRTIS-H observations of the dust coma of comet 67P/Churyumov-Gerasimenko: spectral properties and color temperature variability with phase and elevation
AuthorsInstitution or Email of AuthorsAuthor's ORCID iD
Bockelee-Morvan, D.Observatoire de Paris, MeudonUNSPECIFIED
Filacchione, G.INAF-IASF, Rome, ItalyUNSPECIFIED
Crovisier, J.Observatoire de Paris-Meudon, FranceUNSPECIFIED
Drossart, P.Observatoire de Paris, Meudon, FranceUNSPECIFIED
Arnold, GabrieleGabriele.Arnold (at) dlr.deUNSPECIFIED
Ciarniello, M.inaf-iasf, italyUNSPECIFIED
Kappel, DavidDavid.Kappel (at) dlr.dehttps://orcid.org/0000-0002-0518-5548
Longobardo, Ainaf-laps, via del fosso del cavaliere 100, i-00133 rome, italyUNSPECIFIED
Capria, M. T.Instituto di Astrofisica Spaziale e Fisica Cosmica, Roma, ItalyUNSPECIFIED
De Sanctis, M.C.Istituto Nazionale di Astrofisica, Rome, Italy.UNSPECIFIED
Taylor, F.Oxford UniversityUNSPECIFIED
Date:October 2019
Journal or Publication Title:Astronomy & Astrophysics
Refereed publication:Yes
Open Access:Yes
Gold Open Access:No
In ISI Web of Science:Yes
DOI :10.1051/0004-6361/201834764
Page Range:A22
Publisher:EDP Sciences
Keywords:comets: general; comets: individual: 67P/Churyumov-Gerasimenko; infrared: planetary systems; Astrophysics - Earth and Planetary Astrophysics
HGF - Research field:Aeronautics, Space and Transport
HGF - Program:Space
HGF - Program Themes:Space Exploration
DLR - Research area:Raumfahrt
DLR - Program:R EW - Space Exploration
DLR - Research theme (Project):R - Project ROSETTA Instruments
Location: Berlin-Adlershof
Institutes and Institutions:Institute of Planetary Research > Leitungsbereich PF
Institute of Planetary Research > Asteroids and Comets
Deposited By: Kappel, David
Deposited On:21 Nov 2019 08:39
Last Modified:21 Nov 2019 08:39

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